It is a fundamental principle of trademark law that the first person to actually use a trademark in commerce has priority over that mark. “Use in commerce” is defined by statute to mean “the bona fide use of a mark in the ordinary course of trade.” A mark is deemed to be in use in commerce when it is placed “on the goods or their containers or the displays associated therewith or on the tags or labels affixed thereto.” 

How have courts interpreted this statute in practice?  Can you establish the use of a mark in commerce before you sell any products using that mark? How about years ...